Fiber optic furcation module

ABSTRACT

The invention relates to a fiber optic furcation module, comprising: at least one planar wave guide card; a first adapter assigned to the or each planar wave guide card, the or each first adapter comprising a plurality of adapter ports for optical fibers terminated in an optical fiber ribbon connector; a plurality of second adapters assigned to the or each planar wave guide card, each of said second adapters comprising one adapter port or two adapter ports, the one or two adapter ports being operative to receive respective single optical fiber connectors terminated with single optical fibers; a plurality of fiber optic transmission channels provided by the or each planar wave guide card, the fiber optic transmission channels providing optical traces being operative to transmit and/or receive optical wavelength signals and connecting each adapter port of a first adapter with an adapter port of one of said second adapters.

PRIORITY APPLICATION

This application is a continuation of International Application No.PCT/US10/34298 filed May 11, 2010, which claims the benefit of priorityto European Application No. 09006500.4, filed May 14, 2009, bothapplications being incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a fiber optic furcation module.

BACKGROUND

Corning Cable Systems Plug&Play™ Universal System brand LANscape®Pretium® is a preterminated optical fiber cabling system particularlyused in data center applications. Such a system comprises variouscomponents, including so-called CCH (Closet Connector Housing) modules.A plurality of such CCH modules can be positioned in housing, whereby aplurality of housings can be mounted to a rack. The LANscape® Pretium®system belongs in principle to the prior art.

A CCH module of the LANscape® Pretium® system is used to provide afurcation function, namely to break out a 12 fiber ribbon connectorbeing preferably a MTP connector into simplex or duplex style singlefiber connectors. Such a CCH module comprises one or two first adaptersto which a ribbon fiber connector is connectable. Each first adaptercomprises a plurality of adapter ports for optical fibers terminated ina ribbon fiber connector. Such a CCH module comprises further aplurality of second adapters to which single fiber connectors areconnectable. Each second adapter comprises one adapter port or twoadapter ports for optical fibers terminated in single fiber connectors.A factory-installed and tested optical fiber assembly positioned insidesuch a CCH module connects each adapter port of the or each firstadapter to an adapter port of the second adapters thereby providing thefurcation function or break out function.

The CCH modules known from the prior art have a depth of around 90 mm.For the use of such modules in so-called Next Generation Data Centers(“NGDCs”) the depth of the modules needs to be reduced. NGDCs denotedata centers, which will be smaller, better integrated, of reducedfootprint and with improved ventilation. These factors are needed inorder to decrease the total cost of ownership in collocation rooms forthe operators, facilitate the installers in their work and finallydecrease the power consumption of computer room air conditioners. Inview of the above described tendency, the depth of CCH modules knownfrom the prior art has become too big.

Actions that could be taken with the optical fibers of the optical fiberassembly positioned inside such a CCH module would allow to reduce thedepth to around to 40-50 mm. However, a much smaller depth for such afiber optic furcation module is wanted for the use in NGDCs.

SUMMARY

Against this background, the present invention is based on the object ofproviding a novel fiber optic furcation module having a reduced depth.This problem is solved by a fiber optic furcation module according toclaim 1.

The fiber optic furcation module according to the invention comprises atleast one planar wave guide card; a first adapter assigned to the oreach planar wave guide card, the or each first adapter comprising aplurality of adapter ports for optical fibers terminated in an opticalfiber ribbon connector; a plurality of second adapters assigned to theor each planar wave guide card, each of said second adapters comprisingone adapter port or two adapter ports, the one or two adapter portsbeing operative to receive respective single optical fiber connectorsterminated with single optical fibers; a plurality of fiber optictransmission channels provided by the or each planar wave guide card,the fiber optic transmission channels providing optical traces beingoperative to transmit and/or receive optical wavelength signals andconnecting each adapter port of a first adapter with an adapter port ofone of said second adapters.

The basic idea of the invention is to replace an optical fiber assemblypositioned inside a furcation module by a planar wave guide card.

The planar waveguide card leverages the quickest possible route from theor each first adapter to the second adapters. The permissible benddiameters of the optical fibers of an optical fiber assembly are nolonger critical, since with a planar waveguide card small widths ofoptic transmission channels within the planar waveguide card and tightbend diameters at the same time can be provided. Moreover, the planarwaveguide card reduces the adapter size, which no longer protrudes intothe module. All that leads to a fiber optic furcation module having avery compact depth, which never before has been achieved. The inventionallows reduction of the depth of a fiber optic furcation module to 5-10mm.

According to a preferred embodiment of the invention each adapter portof the or each first adapter and each second adapter comprises a modeconditioning element and a waveguide funnel.

The mode conditioning element provides the conversion of the size of thelight mode to be transmitted within a fiber optic transmission channelof the planar wave guide card.

The waveguide funnel of each adapter port provides a smooth transitionbetween the fiber optic transmission channel of the planar wave guidecard and a fiber core of an optical fiber terminated in a fiber opticconnector being connectable to the respective adapter port.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred developments of the invention are given in the dependentclaims and the description below. Exemplary embodiments will beexplained in more detail with reference to the drawing, in which:

FIG. 1 shows a front view of a fiber optic furcation module according tothe present invention;

FIG. 2 shows a back view of a fiber optic furcation module according tothe present invention;

FIG. 3 shows a schematic cross-sectional view though the fiber opticfurcation module according to the present invention along the directionIII-III in FIGS. 1 and 2;

FIG. 4 shows a preferable layout of a planar waveguide card; and

FIG. 5 shows a detail of an adapter port of the fiber optic furcationmodule according to the present invention including a mode conditioningelement and a waveguide funnel.

DETAILED DESCRIPTION

FIG. 1 shows a front view and FIG. 2 shows a back view of a preferredembodiment of fiber optic furcation module 10 according to presentinvention, whereby FIG. 3 shows a cross-sectional view though said fiberoptic furcation module 10.

The fiber optic furcation module 10 according to FIGS. 1 to 3 comprisestwo first adapters 11 positioned at the back side of the fiber opticfurcation module 10 and a plurality of second adapters 12 positioned atthe front side of the fiber optic furcation module 10. Each firstadapter 11 comprises a plurality of adapter ports 13 for optical fibersterminated in a ribbon fiber connector. Each second adapter 12 comprisestwo adapter ports 14 for optical fibers terminated in single fiberconnectors.

In the preferred embodiment shown in FIGS. 1 to 3, the two firstadapters 11 are designed as MPO adapters, especially as MTP adapters.Each of the two MPO adapters 11 comprises twelve adapter ports 13 fortwelve optical fibers terminated in a ribbon fiber connector.

In the preferred embodiment shown in FIGS. 1 to 3, the second adapters12 are designed as duplex adapters each having two adapter ports 14 fortwo optical fibers each terminated in a single fiber connector.

Each of the twelve adapter ports 13 of an MPO adapter 11 is opticallyconnected to an adapter port 14 of one duplex adapters 12 beingpositioned in a row of six duplex adapters 12.

The fiber optic furcation module 10 according to FIGS. 1 to 3 furthercomprises two planar wave guide cards 15. To each planar wave guide card15 there is assigned one of the first adapters 11 and a plurality of thesecond adapters 12. In the preferred embodiment shown in FIGS. 1 to 3,to each planar wave guide card 15 there is assigned one MPO adapters 11having twelve adapter ports 13 for twelve optical fibers terminated in aribbon fiber connector and six duplex adapters 12 each having twoadapter ports 14 for two optical fibers each terminated in a singlefiber connector.

According to the shown embodiment, the first adapter 11 and saidplurality of second adapters 12 are assigned to opposite sides of eachplanar wave guide card 15. However, it should be noted that it is alsopossible that the first adapter 11 and the plurality of second adapters12 are assigned to the same side of each planar wave guide card 15.

In the preferred embodiment shown in FIGS. 1 to 3, the two planar waveguide cards 15 are mechanically cascaded in a way that a first planarwave guide card 15 is mounted to a supporting frame 20 (see FIGS. 2, 3)and that a second planar wave guide card 15 is mounted to the firstplanar wave guide card 15. The fiber optic furcation module 10 can bemounted to a housing through said supporting frame 20, whereby aplurality of such fiber optic furcation modules 10 are typically mountedto a housing.

The first adapter 11 being preferably a MPO adapter and the plurality ofsecond adapters 12 being preferably duplex adapters which are assignedto each planar wave guide card are halves of standard MPO or standardduplex adapters.

Each planar wave guide card 15 provides a plurality of fiber optictransmission channels 16 running within the respective planar wave guidecard 15 and connecting each adapter port 13 of each first adapter 11 toan adapter port 14 of one of said second adapters 12 assigned to thesame planar wave guide card 15 thereby providing the furcation functionor break out function.

The fiber optic transmission channels 16 of the planar waveguide cards15 provide optical traces being operative to transmit and/or receiveoptical wavelength signals. The planar waveguide cards 15 leverage thequickest possible route from the first adapter 11 to the second adapters12 and allow reduction of the depth d₁₀ of the fiber optic furcationmodule 10 to 5 mm-10 mm.

The permissible bend diameters of optical fibers of an optical fiberassembly are no longer critical (up to 1.6 mm), since with thedescribed, preferred configuration of planar waveguide card 15 smallwidths of optic transmission channels within the planar waveguide card15 and tight bend diameters at the same time can be provided.

A planar waveguide card 15 is a member of the waveguide family, to whichoptical fibers also belong. A planar waveguide card is formed on a plateof substrate. This produces a firm and rigid parallelepiped, which canbe very precisely tailored to the needs. The choice of materials, theirrefractive indexes and other properties are much bigger than in case ofoptical fibers.

The cladding and core of a planar waveguide card are grown or depositedon the substrate. High refractive index difference can be reached, whichleads to an elevated numerical aperture (NA), which in turn allows forlow widths of channels and tight bends at the same time.

FIG. 4 illustrates a preferable layout of the planar waveguide card 15used in the fiber optic furcation module 10 according to the presentinvention. In general, a core of the planar waveguide card 15 is buriedunder the Silicon Glass BPSG and is made of silicone oxynitride SiON.

The refractive index difference is 5%, which together with the thickcladding yields very good transmission capabilities. A substrate of theplanar waveguide card 15 is made of pure silicon Si on which the lowercladding layer made from SiO₂ is grown via oxidation.

The exact dimensions that are given guarantee for the 1550 nm wavelengththe desired bend diameters and transmission properties for the singlemode operation of the waveguide channels 16. However, the dimensions canbe amended within the scope of this invention, e.g. to adapt the deviceto different wavelengths to be transmitted. The distance between fiberoptic transmission channels 16 is approximately 6 μm.

The materials and manufacturing of the planar waveguide card 15 can bechanged. Is possible to manufacture the core of the planar waveguidecard 15 using a sol-gel process, e.g. a metal alkoxide (fluid) issubject to hydrolysis and polymeration, which consequently forms asolid. This is applied to the buried core formation. Further on, it ispossible to interchange the materials only by making use of galliumarsenide or indium phosphide.

It should be noted that other layouts of the planar waveguide card 15can be used. The so-called rib waveguide layout shown in FIG. 4 ispreferred, but the invention is not limited to this layout. Otherlayouts of the planar waveguide card 15 can be a so-called ridgewaveguide layout, or a so-called embedded waveguide layout, or aso-called immersed waveguide layout, or a so-called bulge waveguidelayout, or a so-called strip-loaded waveguide lay, or a so-called metalor buffered metal waveguide layout.

Each adapter port 13, 14 provides a fiber optic interface between afiber optic transmission channel 16 of the respective planar wave guidecard 15 and an optical fiber terminated in a fiber optic connector 11,12 and being connectable to said adapter port 13, 14 by the respectivefiber optic connector 11, 12. Each adapter port 13, 14 (see FIG. 5)comprises a mode conditioning element 17 and a waveguide funnel 18 inorder to provide the desired modes for a low loss coupling.

The mode conditioning element 17 of each adapter port 13, 14 providesthe right size of a mode to be transmitted within the fiber optictransmission channel 16 of the respective planar wave guide card 15, aswell as on the other hand the right size of the mode to be transmittedwithin the optical fiber core 19. The mode conditioning element 17 ofeach adapter port 13, 14 is positioned between a fiber optictransmission channel 16 of the respective planar wave guide card 15running to the adapter port 13, 14 and the waveguide funnel 18 of saidadapter port 13, 14.

The mode conditioning element 17 comprises waveguide stripes 21 that aredeposited perpendicularly to the main transmission channel and arespecially sized and separated to produce a wave broadening antenna. Insuch a way, the initial mode field diameter in a transmission channel iselevated which is needed to feed the wave properly into a fiber core 19.On the other hand, the mode conditioning element 17 acts as a wavethinning antenna. In such a way, the initial mode field diameter in anoptical fiber core 19 is decreased in order to be fed into thetransmission channel 16.

The mode conditioning element 17 provides the conversion of the size ofthe light mode in the following way: When light propagates from theoptical fiber—it reduces the mode field diameter from around 10 μm toaround 4 μm to be transmitted within a fiber optic transmission channelof the planar wave guide card.

When the light propagates from the fiber optic transmission channel ofthe planar wave guide—it increases the mode field diameter from around 4μm to around 10 μm to be transmitted within the optical fiber.

The width w₁₆ of each fiber optic transmission channel 16 of therespective planar wave guide card 15 running to an adapter port 13, 14is smaller than the width w₁₉ of a fiber core 19 of the optical fiberterminated in a fiber optic connector being connectable to said adapterport 13, 14.

The waveguide funnel 18 of each adapter port 13, 14 provides a smoothtransition between the fiber optic transmission channel 16 of therespective planar wave guide card 15 running to an adapter port 13, 14and the fiber core 19 of the optical fiber terminated in a fiber opticconnector being connectable to said adapter port 13, 14.

The waveguide funnel 18 is a 3D structure, on which the fiber core's 19circumference is almost circumscribed. The waveguide funnel 18 can beproduced by an etching process.

In the preferred embodiment, each optic transmission channel 16 providedby a planar wave guide card 15 comprises a width W₁₆ of approximately 3μm, wherein each fiber core 19 of each optical fiber terminated in afiber optic connector comprises a width w₁₉ of approximately 8 μm, andwherein the funnel 18 comprising a length l₁₈ of approximately 10 μmproviding a smooth transition between the fiber optic transmissionchannel 16 and the fiber core 19. The mode conditioning element 17comprising the waveguide stripes 21 comprising a length l₁₇ ofapproximately 140 μm, whereby the width w₂₁ of the waveguide stripes 21is varying between approximately 1 μm and approximately 18 μm andwhereby the thickness of the waveguide stripes 21 is approximately 2.7μm.

Naturally, the design of the adapter ports 13, 14 according to FIG. 4 isused on both sides of the module (multifiber and singlefiber), as thelight wave can be sent via it in either direction.

What is claimed is:
 1. A fiber optic furcation module, comprising atleast one planar wave guide card; a first adapter assigned to the atleast one planar wave guide card, the first adapter comprising aplurality of adapter ports for optical fibers terminated in an opticalfiber ribbon connector; a plurality of second adapters assigned to theat least one planar wave guide card, each of said second adapterscomprising one adapter port or two adapter ports, the one or two adapterports being operative to receive respective single optical fiberconnectors terminated with single optical fibers; a plurality of fiberoptic transmission channels provided by the at least one planar waveguide card, the fiber optic transmission channels providing opticaltraces being operative to transmit and/or receive optical wavelengthsignals and connecting each adapter port of said first adapter with atleast one of said one adapter port or said two adapter ports of one ofsaid second adapters.
 2. The fiber optic furcation module as claimed inclaim 1, wherein the first adapter assigned to the at least one planarwave guide card is an MPO adapter.
 3. The fiber optic furcation moduleas claimed in claim 1, wherein said second adapters assigned to the atleast one planar wave guide card are simplex adapters each having oneadapter port for one optical fiber terminated in a single fiberconnector.
 4. The fiber optic furcation module as claimed in claim 1,wherein said plurality of second adapters assigned to the at least oneplanar wave guide card are duplex adapters each having two adapter portsfor two optical fibers each terminated in a single fiber connector. 5.The fiber optic furcation module as claimed in claim 4, wherein eachadapter port provides a fiber optic interface between a fiber optictransmission channel of a respective one of the at least one planar waveguide card and an optical fiber terminated in a fiber optic connectorand being connectable to said adapter port by the respective fiber opticconnector.
 6. The fiber optic furcation module as claimed in claim 5,wherein each adapter port comprises a mode conditioning element and awaveguide funnel.
 7. The fiber optic furcation module as claimed inclaim 6, wherein said mode conditioning element of each adapter portreduces a mode field diameter from around 10 μm to around 4 μm to betransmitted within the fiber optic transmission channel of the planarwave guide card.
 8. The fiber optic furcation module as claimed in claim6, wherein said mode conditioning element of each adapter port increasesa mode field diameter from around 4 μm to around 10 μm to be transmittedwithin a fiber core of the optical fiber terminated in a fiber opticconnector being connectable to said adapter port.
 9. The fiber opticfurcation module as claimed in claim 6, wherein the mode conditioningelement of each adapter port is positioned between a fiber optictransmission channel of the respective one of the at least one planarwave guide card running to the adapter port and the waveguide funnel ofsaid adapter port.
 10. The fiber optic furcation module as claimed inclaim 9, wherein the width of each fiber optic transmission channel ofthe respective one of the at least one planar wave guide card running toan adapter port is smaller than the width of a fiber core of the opticalfiber terminated in a fiber optic connector being connectable to saidadapter port.
 11. The fiber optic furcation module as claimed in claim10, wherein the waveguide funnel of each adapter port provides a smoothtransition between the fiber optic transmission channel of a respectiveone of the at least one planar wave guide card running to an adapterport and the fiber core of the optical fiber terminated in a fiber opticconnector being connectable to said adapter port.
 12. The fiber opticfurcation module as claimed in claim 11, wherein each optic transmissionchannel provided by the at least one planar wave guide card comprises awidth of approximately 3 μm, wherein each fiber core of each opticalfiber terminated in a fiber optic connector comprises a width ofapproximately 8 μm, and wherein the waveguide funnel comprising a lengthof approximately 10 μm provides a smooth transition between the fiberoptic transmission channel and the fiber core.
 13. The fiber opticfurcation module as claimed in claim 1, wherein said first adapter andsaid plurality of second adapters are assigned to opposite sides of theat least one planar wave guide card.
 14. The fiber optic furcationmodule as claimed in claim 1, wherein said first adapter and saidplurality of second adapters are assigned to the same side of the atleast one planar wave guide card.
 15. The fiber optic furcation moduleas claimed in claim 1, comprising two mechanically cascaded planar waveguide cards, each comprising a first adapter, a plurality of secondadapters and fiber optic transmission channels, whereby a first planarwave guide card is mounted to a supporting frame and whereby a secondplanar wave guide card is mounted to the first planar wave guide card.16. The fiber optic furcation module as claimed in claim 1, wherein thefirst adapter assigned to each planar wave guide card is an MTP adapter.17. A fiber optic furcation module, comprising at least one planar waveguide card; a first adapter assigned to the at least one planar waveguide card, the first adapter comprising a plurality of adapter portsfor optical fibers terminated in an optical fiber ribbon connector; aplurality of second adapters assigned to the at least one planar waveguide card, each of said second adapters comprising one adapter port ortwo adapter ports, the one or two adapter ports being operative toreceive respective single optical fiber connectors terminated withsingle optical fibers; a plurality of fiber optic transmission channelsprovided by the at least one planar wave guide card, the fiber optictransmission channels providing optical traces being operative totransmit and/or receive optical wavelength signals and connecting eachadapter port of said first adapter with at least one of said one adapterport or said two adapter ports of one of said second adapters; whereineach adapter port provides a fiber optic interface between a fiber optictransmission channel of a respective one of the at least one planar waveguide card and an optical fiber terminated in a fiber optic connectorand being connectable to said adapter port by the respective fiber opticconnector; and wherein each adapter port comprises a mode conditioningelement and a waveguide funnel.
 18. The fiber optic furcation module asclaimed in claim 17, wherein the mode conditioning element compriseswaveguide stripes.
 19. The fiber optic furcation module as claimed inclaim 18, wherein the waveguide stripes are deposited perpendicular tothe fiber optic transmission channel.
 20. The fiber optic furcationmodule as claimed in claim 18, wherein the waveguide stripes arespecially sized and separated to produce one of a wave broadeningantenna and a wave thinning antenna.